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Porous silica particles have shown applications in various technological fields including their use as catalyst supports in heterogeneous catalysis. The mesoporous silica particles have ordered porosity, high surface area, and good chemical stability. These interesting structural or textural properties make porous silica an attractive material for use as catalyst supports in various heterogeneous catalysis reactions. The colloidal nature of the porous silica particles is highly useful in catalytic applications as it guarantees better mass transfer properties and uniform distribution of the various metal or metal oxide nanocatalysts in solution. The catalysts show high activity, low degree of metal leaching, and ease in recycling when supported or immobilized on porous silica-based materials. In this overview, we have pointed out the importance of porous silica as catalyst supports. A variety of chemical reactions catalyzed by different catalysts loaded or embedded in porous silica supports are studied. The latest reports from the literature about the use of porous silica-based materials as catalyst supports are listed and analyzed. The new and continued trends are discussed with examples. [ABSTRACT FROM AUTHOR]

Mesoporous silica-included heteropolyacids materials were synthesized and characterized by nitrogen sorption, XRD, FT-IR, TEM and NH 3 -TPD. Characterization results show that silica included heteropolyacids is a kind of Bronsted acid catalyst possessing large surface area, suitable pore structure, appropriate acid strength and high acid density. These materials are used as solid catalysts for the alkylation of phenol with cyclohexene. The mesoporous channel facilitates not only the dispersion of Bronsted acidity centers but also the transport of reactant and product molecules, thus leading to a significantly improved catalytic performance. Through adjusting the interaction between the support pore channel surface and heteropolyacid acive species, different acidity amount and strength can be obtained, leading to the tunable selectivity to the alkylation of phenol with cyclohexene. The improvement of reusability of silica-included HPA catalyst was related to the uniform dispersion of HPA and the enhanced interaction between HPA and the support. In six cycles of the catalyst, a stable activity could be mainttained. [ABSTRACT FROM AUTHOR]

A new class of polymeric colloids, multiple suspension particles (MSP), with a size of several micrometers consisting of many small polystyrene particles with a diameter below 100 nm grown in a poly (N-isopropyl acrylamide) precursor scaffold is obtained, as reported in our previous paper. Herein, the unique MSP are applied as template for silica nanocasting and hierarchically organized porous silica with raspberry-like aggregation structure is obtained. The aggregates with a diameter of about 1 μm are composed of thousands of hollow silica particles, which are with a size of about 70 nm originating from polystyrene particles and with mesopores of about 5.8 nm on the shell from PNIPAM chains. The aggregates have high specific surface area and pore volume. With the advantage of high mass transport contributed by macropores and of high specific surface area due to mesopores, the hierarchically organized structure has great potential application in catalysis field. [ABSTRACT FROM AUTHOR]

Removal of toxic effluents (like dyes and pesticides) by cost-effective and user-friendly method is needed to provide sustaining the environment for civilization. Here, low-cost mesoporous silica monolith (SiO 2 ) and silica supported metal-oxide (ZnO@SiO 2 ) monolith were synthesized to reduce the solemn impact of toxic effluents. Batch experiments were performed to remove Alizarin (AZ), Paradol (PD), Acid blue-113 (AB) and Rhodamine-B (RD) from aqueous solution via synthesized monoliths. The influence of various parameters (like pH, contact time, temperature and adsorbate concentration) has been optimized. The maximum adsorption capacity of ZnO@SiO 2 monolith is 625, 500, 714 and 555 mg/g for AZ, RD, AB, and PD respectively. The adsorption for AZ, PD, AB, and RD is spontaneous and exothermic. The adsorption process can be well described by the pseudo-second-order kinetic model (high regression coefficients) and the Freundlich isotherm model (R 2 = 0.97–0.99). [ABSTRACT FROM AUTHOR]

In the present study, ordered hierarchically porous silica (by sol-gel method) and metal-oxide monoliths (through nanocasting method) were synthesized. Porous silica and metal oxide monoliths (MnO 2 and TiO 2 ) exhibited excellent adsorption for heavy metal ions such as Pb(II) & Cd(II). The morphological and structural study of the synthesized silica and metal oxide monoliths were done by FESEM and XRD analysis. The adsorption studies were conducted in different batches. The maximum adsorption of Pb(II) on SiO 2 , MnO 2 and TiO 2 varied from 91 to 125, 166–200 and 769–857 mg/g respectively depending upon the choice of PEG, which is used as a structure directing/controlling agent. Similarly the maximum adsorption of Cd(II) on SiO 2 , MnO 2 and TiO 2 varied from 90 to 100, 100–125 and 667–770 mg/g respectively. The effects of contact time (0–80 min), temperature (at 303, 313 and 323 K) and pH (3–10) on the Pb(II) & Cd(II) removal were also explored. [ABSTRACT FROM AUTHOR]

In this work, pH-sensitive “dual-switch” porous silica (pSiO 2 ) nanoparticles (NPs) were constructed for drug delivery. Poly(acrylic acid) (PAA) was grafting onto the internal and external surfaces of amino groups functionalized porous silica (pSiO 2 -NH 2 ) NPs by the amidation between the amino groups and the carboxyl groups of PAA for pH triggered drug release. The resultant pSiO 2 /PAA NPs have an average diameter of 50–60 nm and high specific surface area (914 m 2 ·g − 1 ). To improve the loading capacity, ZnO quantum dots (QDs) were used to block the partial pores of pSiO 2 /PAA and the loading capacity reached to 28% for methotrexate (MTX) model drug. The in vitro cellular cytotoxicity test and a hemolysis assay demonstrated that the pSiO 2 /PAA/ZnO NPs were highly biocompatible and suitable to utilize as drug carriers. The MTX-loaded pSiO 2 /PAA/ZnO NPs displayed more efficient cytotoxic to HepG2 cells than free MTX. The pSiO 2 /PAA/ZnO NPs displayed low premature, pH-responsive release and pH-dependent fluorescence. Moreover, pH-dependent fluorescence enables to trace MTX release behavior. [ABSTRACT FROM AUTHOR]

Tetrahedral Sn built into microporous silica frameworks such as zeolites and structured mesoporous silica can be used as heterogeneous Lewis acid catalysts. These materials have recently attracted much attention, as they show remarkable activity and selectivity in a wide range of reactions. A prominent example is the conversion of carbohydrates into platform and commodity chemicals such as lactic acid or alkyl lactates, where the activity and selectivity of Sn-based materials remains unsurpassed compared to Sn-free catalysts. Some of the materials show water-tolerant behavior and can therefore also be used in aqueous systems. In this work, a literature overview regarding synthesis of Sn-containing silica materials is given, as well as a synopsis of the characterization tools which can be used to unravel the structure of the catalytic active site. The application of such Sn-containing materials for diverse catalytic reactions is reviewed, with special emphasis on the effects of the catalyst characteristics on the catalytic activity and stability. [ABSTRACT FROM AUTHOR]

Two types of polymeric ionic liquids (PILs) modified porous silica for CO2 sorption were synthesized by the polymerization of dialkylphosphate di-butyl phosphate [VYIM][Bu2PO4] and 1-allyl-3-methylimidazolium tetrafluoroborate [AMIM][BF4] with alkoxyl-modified silica. The PILs-modified silica (SiO2-P[VYIM][Bu2PO4] and SiO2-P[AMIM][BF4]) were evaluated by CO2 adsorption isotherms at 273 K for investigating the porous structures. The adsorption and desorption behaviors of CO2 (at 298, 313, and 333 K) and N2 (at 313 K) up to 0.2 MPa were also investigated using a gravimetric method. In comparison with bare silica, the grafting of PILs on the support surface leads to a loss of microporosity, resulting in a slight decrease in CO2 sorption capacity. The difference of CO2 sorption capacity between SiO2-P[VYIM][Bu2PO4] and SiO2-P[AMIM][BF4] is little, especially under 0.1 MPa. CO2/N2 selectivity is however notably improved, and especially [AMIM][BF4] modified silica shows the best performance. The homogeneous surface diffusion model (HSDM) was used to estimate the diffusivities and good agreement between experimental values and fitting curves was obtained. The diffusion coefficients of CO2 in the PILs-modified silica are level with that of bare silica at level of 10−7−10−8 m2/s, about two to three orders of magnitude faster than that of reported [BMIM][BF4]. POLYM. COMPOS., 38:759-766, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In this study, within a sustainable chemistry approach, a clean and eco-friendly synthesis process of silica monoliths compatible with environmental limitations is developed. Rice husk (RH), a surplus agricultural byproduct, was used to engineer monoliths with a hierarchical pore structure. Amorphous and crystalline silica powders were extracted from rice husk and ice-templated using water as a liquid vehicle. The effect of silica crystallinity and silica content, as well as processing parameters such as the freezing rate and sintering temperature on the microstructural characteristics and mechanical properties of the obtained monoliths were investigated. Depending on the freezing regime, microstructural analysis confirmed the formation of macropores with lamellar or honeycomb-like structures. By varying the processing parameters, the pore size, wall thickness and porosity can be tailored. While monoliths from crystalline rice husk ash (CRHA) show higher mechanical strength, monoliths from amorphous rice husk ash (ARHA) possess a high specific surface area, demonstrating aligned nano-channels and non-uniform mesoporosity. [ABSTRACT FROM AUTHOR]

In this study, the monodisperse large-porous silica microspheres were successfully synthesized with polymer microspheres as the templates and characterized. The functionalization of the P GMA-EDMA microspheres was carried out with TEPA to generate amino groups. Subsequently, TEOS was readily hydrolyzed to form Si-containing low molecular weight species with ammonia as a catalyst. The low molecular weight species could be attracted by the amino groups and deposited into the functionalized P GMA-EDMA microspheres to form polymer/silica hybrid microspheres. Finally, the monodisperse large-porous silica microspheres were obtained with controllable morphology and structure after calcination to remove the templates. Using this method, the agglomeration of the hybrid microspheres was overcome, and the yield of 95.7% of the monodisperse large-porous silica microspheres was achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with ODS and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The high column efficiency and good reproducibility suggested that the large-porous silica microspheres could be used as a matrix for protein separation. [ABSTRACT FROM AUTHOR]

A sol–gel process was used to produce hierarchical porous silica (HPS) with and without the use of natural rubber (NR) particles as a templating material. The effects of the following factors on the pore properties are reported: the template-to-silica ratio, the template removal method (either calcination or solvent extraction), the pH, and the source of the NR latex. HPS with macropores formed when the NR template was used. The template affected only the interspacing of silica agglomerates but not the spacing within them. Calcination proved to be more effective than the solvent extraction in removing the template and did not damage the HPS morphology. The pH affected not only the formation of primary silica particles, but also the interactions between the NR template and the primary silica particles. This reduced the BET surface area and the number of macropores in HPS produced at a higher pH. The latex source (whether from a single plantation or mixed latex from multiple plantations) had barely any effect on the properties of the HPS. [ABSTRACT FROM AUTHOR]

New hybrid organic-inorganic mesoporous silicas were prepared by employing three different synthesis routes and mercury adsorption studies were done in aqueous media using the batch technique. The organic ligands employed for the functionalization were derivatives of 2-mercaptopyrimidine or 2-mercaptothiazoline, and the synthesis pathways used were post-synthesis, post-synthesis with surface ion-imprinting and co-condensation with ion-imprinting. The incorporation of functional groups and the presence of ordered mesopores in the organosilicas was confirmed by XRD, TEM and SEM, nitrogen adsorption-desorption isotherms, 13 C MAS-NMR, 29 Si MAS-NMR, elemental and thermogravimetric analysis. The highest adsorption capacity and selectivity observed was for the material functionalized with 2-mercaptothiazoline ligand by means the co-condensation with ion-imprinting route (1.03 mmol g −1 at pH 6). The prepared material could be potential sorbent for the extraction of this heavy metal from environmental and drinking waters. [ABSTRACT FROM AUTHOR]

A slurry-based method was developed for the entrapment of alpha 1 -acid glycoprotein (AGP) for use in high-performance affinity chromatography to study drug interactions with this serum protein. Entrapment was achieved based on the physical containment of AGP in hydrazide-activated porous silica supports and by using mildly oxidized glycogen as a capping agent. The conditions needed for this process were examined and optimized. When this type of AGP column was used in binding studies, the association equilibrium constant ( K a ) measured by frontal analysis at pH 7.4 and 37 °C for carbamazepine with AGP was found to be 1.0 (±0.5) × 10 5 M −1 , which agreed with a previously reported value of 1.0 (±0.1) × 10 5 M −1 . Binding studies based on zonal elution were conducted for several other drugs with such columns, giving equilibrium constants that were consistent with literature values. An entrapped AGP column was also used in combination with a column containing entrapped HSA in a screening assay format to compare the binding of various drugs to AGP and HSA. These results also agreed with previous data that have been reported in literature for both of these proteins. The same entrapment method could be extended to other proteins and to the investigation of additional types of drug-protein interactions. Potential applications include the rapid quantitative analysis of biological interactions and the high-throughput screening of drug candidates for their binding to a given protein. [ABSTRACT FROM AUTHOR]

Advanced materials for molecular sensing, selective adsorption and heterogeneous catalysis require fine control at the surface–fluid interface. To achieve this objective several aspects of the material have to be considered: (i) the molecular structure of the active sites, (ii) their vicinity at the nanometer scale of length, (iii) their distribution in the solid and (iv) the confinement controlled by the size and shape of pores. The approaches developed to synthesise such materials are reviewed here considering mainly mesoporous templated silicas such as MCM-41, SBA-15 and related materials. In addition, a new nomenclature (InGASE) is proposed to classify hybrid or non-hybrid materials depending on the location of the function in the porous solid support and the nature of the linker. Special attention is devoted to the different strategies described in the literature to control the grafting or anchoring of organic functions and metal complexes. The challenge is to obtain isolated and well-defined unique sites in a confined nanometric space with an appropriate environment. Applications of these materials in the fields of catalysis, adsorption, sensing and drug delivery are briefly surveyed. [ABSTRACT FROM AUTHOR]

An efficient acidic functionalization of mesoporous silica LUS-1 (Laval University silica) was carried out by grafting and oxidation of (3-mercaptopropyl)trimethoxysilane. The functionalized LUS-1 was characterized by different methods such as TGA, XRD, BET and SEM methods and its catalytic activity for one-pot synthesis of xanthene derivatives via the three-component condensation reaction of aromatic aldehydes and dimedone has been reported. The short reaction time, excellent yields, simple work-up procedure, and environmentally friendly conditions are particular advantages of this method. Antibacterial and antifungal activities of synthesized compounds were measured against gram-positive and gram-negative bacteria and fungus. Only compound 9-(2,4-dichlorophenyl)-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-1 H-xanthene-1,8(2 H)-dione ( 3h) showed activity against Bacillus subtilis. [ABSTRACT FROM AUTHOR]

The exciton confinement effect in quantum dots at the surface of SiO spheres and the percolation phase transition in films based on a mixture of pure SiO spheres and spheres covered by CdS quantum dots (SiO/CdS nanoparticles) are studied. It is found that, due to the high surface energy of spheres, the quantum dots deposited onto their surface are distorted, which modifies the exciton confinement effect: the effect is retained only in one direction, the direction normal to the surface of the spheres. As a result, the energy of the exciton ground state exhibits a complex dependence on both the quantum-dot radius and sphere size. In the optical spectra of films based on this mixture, the clustering of small-sized nanoparticles and then, at a critical concentration of nanoparticles of ~60%, the formation of a percolation cluster are detected for the first time. The critical concentration is twice higher than the corresponding quantity given by the model of geometrical 'colored percolation', which is a consequence of interaction between submicrometer nanoparticles. The relation between the basic parameters of the percolation transition, such as the film porosity, coordination number, and the quantity defining the number of particles in the percolation cluster, is obtained and analyzed. [ABSTRACT FROM AUTHOR]

Porous silicates were synthesized by a nonhydrothermal method, using sodium silicate as a source of silica and cetyltrimethylammonium bromide as a template agent. Catalysts were characterized using thermogravimetric analysis, N2 physisorption, X-ray diffraction, FTIR spectroscopy, pyridine adsorption, potentiometric titration with n-butylamine, scanning electronic microscopy, and transmission electronic microscopy. The surface area of the materials synthesized was greater than 800 m2/g. The introduction of zirconium atoms within the porous silicates increased their acid strength from −42 to 115 mV, while the addition of sulfate ions raised this value to 470 mV. The catalytic activity for the dehydration of alcohols yields conversions of up to 70% for ethanol and 30% for methanol. [ABSTRACT FROM AUTHOR]

A series of heterogemini surfactants C16H33OCH2CH(OH)CH2N+(CH3 )2CnH2n+1 ·Br- were used as the template to synthesise porous silica materials via a Stöber method. The influence of the alkyl chain length of heterogemini surfactants on the morphology of porous silica materials was studied. Porous silica materials were characterised by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption analysis. Results showed that with the increase of alkyl chain length, the morphologies of porous silica materials gradually transform from sphere to sphere with cavity, sphere composed of vesicles, coral like and finally to lamella. Pore size of materials ranges from 1.17 to 3.93 nm. When the alkyl chain is short enough (n = 8 and 10), a hierarchical pore size distribution can be obtained. The possible formation mechanism of the porous silica materials has been discussed. [ABSTRACT FROM AUTHOR]

A novel cyclodextrin intermediate, mono-2A-allylcarbamido-2A-deoxy-permethylated β-cyclodextrin, was synthesized by reacting allylamine and newly prepared mono-2A-azido-2A-deoxy-permethylated β-cyclodextrin by the Staudinger reaction and anchored onto porous silica beads by a one-pot hydrosilylation and immobilization procedure to afford a novel chiral stationary phase. This stationary phase acts as a new member of the previous chiral stationary phase series immobilized on the cyclodextrin C2 position. This stationary phase depicted enantiomeric separation abilities toward a series of bicyclic and tricyclic racemates under reversed-phase conditions. The resolutions for hesperetin and naringenin achieved on the current phase reached 3.91 and 1.11, respectively, much higher than the previous permethylated β-cyclodextrin with the linkage at the C6 position. [ABSTRACT FROM AUTHOR]

In this paper, the effect of layer charge (LC) of base clay on the structural properties of porous clay heterostructures (PCHs) was studied. Three natural montmorillonites (Mt) with different LC and a series of reduced-charge Mt were used in the synthesis of PCH to discuss the non-micellar template model for PCH from the perspective of base clay. The PCH samples are the intergrowth of a porous silica-intercalated clay and an amorphous silica component. The XRD and TEM studies revealed that the d001-values of PCH samples prepared from natural Mt (simply as “natural PCH” for short) were larger than 3 nm. The interstratified structures in PCH samples from reduced-charge Mt (simply as “reduced-charge PCH” for short) were the result of the collapse of interlayer spaces caused by the inhomogeneous LC reduction. The organic carbon contents ( f OC ) of organo-montmorillonite (OMt) were negatively correlated with the bulk silica contents ( f SiO 2 -b ) of the corresponding PCH samples. For the natural PCH, the extra spaces from decreased surfactant within interlayer were occupied by amorphous silica in the pillaring reaction. The decreased specific surface area (SSA), porosity and the invariant dominant pore size (1.3–1.4 nm) of PCH suggested that blocking the pore channels in the interlayer spaces with increased silica was more pronounced than propping the layers permanently apart and building porous structures. Based on the effect of organic template and base clay on the structural properties in our previous and present work, Mt-based PCH probably is a type of porous materials with invariant pore size. [ABSTRACT FROM AUTHOR]

Benzo-18-crown-6 ether resin embedded in porous silica beads was synthesized and used as the packing material for chromatographic separation of 48 Ca isotope. The aim of the present work is to develop efficient isotope enrichment process for double β decay nuclide 48 Ca. To this end, ethanol/HCl mixed solvent was selected as the medium for the chromatographic separation. Adsorption of calcium on the resin was studied at different HCl concentrations and different ethanol mixing ratios in batch-wise experiments. A very interesting phenomenon was observed; Ca adsorption is controlled not by the overall HCl concentration of the mixed solvent, but by the initial concentration of added HCl solution. Calcium break-through chromatography experiments were conducted by using 75 v/v% ethanol/25 v/v% 8 M HCl mixed solvent at different flow rates. The isotope separation coefficient between 48 Ca and 40 Ca was determined as 3.8 × 10 −3 , which is larger than that of pure HCl solution system. Discussion is extended to the chromatographic HETP, height equivalent to a theoretical plate. [ABSTRACT FROM AUTHOR]

A novel dopamine-functionalized mesoporous silica (DMS), synthesized by grafting dopamine onto a mesoporous molecular sieve (SBA-15), was developed as a sorbent to extract U(VI) from aqueous solution. The method used to modify SBA-15 was simple, facile and cost-effective. The DMS was characterized by SEM, TEM, XRD and BET, showing that the material had an ordered mesoporous structure and a large surface area. The effect of contact time, pH, ionic strength, temperature, and solid–liquid ratio on the sorption process was investigated. It was demonstrated that the adsorption of U(VI) by DMS was fast and that it can be described by the pseudo-second order-equation where the equilibrium time was 20 min. Additionally, the adsorption isotherm data were fitted well by the Langmuir model with the maximum adsorption capacity of DMS of 196 mg/g at pH 6.0. Furthermore, the influence of the K + and Na + concentrations and solid-to-liquid ratio on the sorption was very weak, and the values of the thermodynamic parameters revealed that the sorption process was exothermic and spontaneous. All the results suggested that the DMS could be used as an excellent adsorbent to remove U(VI) from aqueous solution. [ABSTRACT FROM AUTHOR]

The osteoconduction of porous bodies made of two kinds of calcium phosphate compounds was investigated by performing single level posterolateral spinal fusions on 20 New Zealand white rabbits. The animals were divided into two groups and implanted with bone graft substitute made of hydroxyapatite (HA) and β-calcium pyrophosphate (β-CPP) respectively. All animals were sacrificed after 12 weeks of surgery, and the fused bone masses were evaluated using manual palpation, uniaxial tensile strength measurement and histological evaluation. Fusion ratios and mean tensile strengths were similar for both β-CPP and HA group. Light and scanning electron microscopy showed new bone growth into the pores, which was abundant in the both β-CPP and HA group. However, the pore size of the β-CPP implant was larger than that of HA, and faster bone growth was observed as β-CPP was absorbed into the host's body. In conclusion, porous β-CPP implants showed more desirable bone graft substitute characteristics due to their satisfactory osteoconductive ability and better biodegradation compared to porous HA implants. [ABSTRACT FROM AUTHOR]

A macroporous silica with azimuthallyshifted double-diamond frameworkshas been synthesized by the self-assembly of an amphiphilic ABC triblockterpolymer poly(tert-butyl acrylate)-b-polystyrene-b-poly(ethylene oxide) and silica sourcein a mixture of tetrahydrofuran and water. The structure of the macroporoussilica consists of a porous system separated by two sets of hollowdouble-diamond frameworks shifted 0.25calong ⟨001⟩and adhered to each other crystallographically due to the loss ofthe mutual support in the unique synthesis, forming a tetragonal structure(space group I41/amd).The unit cell parameter was changed from a= 168to ∼240 nm with c= √2aby tuning the synthesis condition and the wide edge of the macroporesize was ∼100 to ∼140 nm. Electron crystallography wasapplied to solve the structure. Our studies demonstrate electron crystallographyis the only way to solve the complex structure in such length scale.Besides, this structure exhibits structural color that ranged fromviolet to blue from different directions with the bandgap in the visiblewavelength range, which is attributed to the structural feature ofthe adhered frameworks that have lower symmetry. Calculations demonstratethat this is a new type of photonic structure. A complete gap canbe obtained with a minimum dielectric contrast of 4.6, which is inferiorto the single diamond but superior to the single gyroid structure.A multilayer core–shell bicontinuous microphase templatingroute was speculated for the formation of the unique macroporous structure,in which common solvent tetrahydrofuran in hydrophobic shell and selectivesolvent water in hydrophilic core to enlarge each microphase sizes. [ABSTRACT FROM AUTHOR]

The Brønsted acidic imidazolium-based metal-free and halogen-free ionic liquid hydrogen sulfate was immobilized on nanoporous silica SBA-15. The structures of synthesized catalysts were investigated using different characterization techniques, including FT-IR, small angle XRD, SEM, TEM and TGA. The [MPIm][HSO 4 ]@SBA-15 is used as an alternative to conventional catalysts in the Knoevenagel–Michael-cyclization processes for the synthesis of tetrahydrochromenes and hexahydroquinoline carboxylates via a multicomponent procedure. The reaction time is reduced drastically and the reaction is progressed in an environmentally friendly way. The immobilized catalyst can be recycled without substantial loss of activity after seven runs. [ABSTRACT FROM AUTHOR]

This research reported a micelle/microemulsion bimodal templating method to synthesize hierarchical porous silicas (HPS) by using a P123/cosurfactant/1,3,5-trimethylbenzene/water four-component microemulsion system. The influence of different diols (i.e., ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentadiol, and 1,6-hexanediol) as cosurfactants on the synthesis of HPS was systematically investigated. Among the obtained mesoporous silica materials, the HPS materials with pore structures of disordered-SBA-15-type (Dis-SBA-15) together with mesocellular foams (MCFs) could be clearly identified from the TEM images when using ethanediol, 1,3-propanediol, or 1,4-butanediol as the swelling agent of P123 in the initial synthesis environment, while MCFs were the main phases as using 1,5-pentadiol and 1,6-hexanediol. The results showed that those shorter chain diols with carbon number from 2 to 4 (involving ethanediol, 1,3-propanediol, and 1,4-butanediol) could more easily swell the P123 micelles compared with the longer chain diols (1,5-pentadiol and 1,6-hexanediol). Consequently, HPS materials with large pore volumes (up to 1.48 cm³ g-1) were successfully prepared by the oriented role from the templates of the swollen P123 micelles and TMB/P123 microemulsions. This approach provides a novel pathway for the facile synthesis of HPS materials with large pore volumes which may be a type of promising candidate for various applications. [ABSTRACT FROM AUTHOR]

In this study, a novelly synthesized magnetic mesoporous silica composite with high uniformity and polyaniline (PANI) grafted was successfully applied to highly efficient Cr(VI) removal. With the assistance of high adsorption capacity of protonated PANI and the magnetic mesoporous composite at low pH, Cr(VI) was adsorbed and then reduced to less toxic Cr(III) by PANI. The resultant adsorbent was characterized by TEM and FTIR, nitrogen adsorption-desorption measurements were carried out, and the zeta potentials of the prepared adsorbent were also measured at different pH. The adsorption and synergistic reduction route was particularly deduced by analyzing the existing forms of PANI and Cr by XPS. Pseudo-second-order model could well fit the data obtained from batch Cr(VI) removal experiments for the kinetic study, and Langmuir model well described the sorption isotherms with the maximum adsorption capacity of 193.85 mg/g. Competition from coexisting ions (K+, Na+, Ca2+, Cl-, SO42-, NO3-) was proved to be insignificant. Moreover, the exhausted adsorbent could be well regenerated and kept above 83% removal efficiency in the first three cycles, which demonstrated that it was cost-effective. The results suggested that this novel magnetic adsorbent may offer a simple adsorption and synergistic reduction treatment option to remove Cr(VI) contamination from industrial wastewater and natural water bodies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Compared with conventional method, PCSA method yields KIT-6 with tunable pore size of 8–10nm, and. [•] Improved ordering with increased interval time (1–5h) for a given addition combination of 7-xh-3. [•] Higher meso-orderings, when prepared with hydrothermal treatment at 140°C. [•] Particle sizes 1–2 orders of magnitude smaller. [•] Simplicity and directness without changing other synthetic conditions. [ABSTRACT FROM AUTHOR]

Silica-graphene oxide composites were synthesized by hydrothermal method with simultaneous functionalization and reduction of graphene oxide (GO) in the presence of mesoporous silica. Two types of silica were used in the study, mesoporous synthetic silica (MSU-F) synthesized by sol-gel method and mesoporous mineral silica (meso-celite) from pseudomorphic synthesis. The infrared spectra of the composites showed the disappearance of the carboxyl peak at 1735 cm which could be due to the reduction of the -COOH group. The enhancement of the band at 1385 cm is attributed to the vibration of the Si-O-C=O moiety formed by reaction of the -COOH group of GO and the silanol (Si-OH) of silica. The Raman spectra of the composites show a diminished intensity ratio of D to G band indicating that GO was reduced to graphene sheets. The TEM images demonstrate the coupling of silica to GO surface revealing dense loading of silica on GO in planar structure. [ABSTRACT FROM AUTHOR]

Abstract: This study presents a novel approach for the synthesis of porous calcium silicate hydrate (CSH) at a low hydrothermal temperature of 110°C based on enhanced reactivity SiO2 (i.e. silica/polyethylene glycol (PEG2000) composites) as the source silica material. The as-prepared CSH materials exhibited a porous microstructure with a large number of small mesopores. The porosity formation mechanism of CSH was apparent that cavitation, resulting from sonication, enabled PEG2000 (via intercalation on silica) to break apart Si–O–Si structural units, thereby enhancing SiO2 reactivity at a low hydrothermal temperature. In addition, the presence of PEG2000 effectively prevented the aggregation of particles during the formation process of the porous CSH solid. The low temperature synthesis proposed herein represents a viable and effective method for the further development of porous CSH as a functional ceramic material. [Copyright &y& Elsevier]

Novel metal nanoporous transition metal oxides MO (CoO, CuO) have been synthesized by thermal decomposition of inorganic salts precursors (acetates, nitrates) impregnated into hexagonal mesoporous silica (OMS, ordered mesoporous silica) of SBA-15 type (prepared in-house) at different precursor loadings, the mesocomposites thus obtained being monitored after each impregnation-calcination step by small and wide angle powder XRD. The pore size for the ordered silica host range from 5.08 to 7.06 nm. Retention of the hexagonal silica framework has been observed in spite of the temperatures up to 500 °C. Mesoporous CoO has been obtained by leaching the silica through overnight HF dissolution, which partially preserved the small-range ordering found in the parent CoO@OMS composite prior to leaching. Both CoO ( meso) and CoO@SBA-15 have been tested in methane oxidation and were found to be superior to the bulk CoO performance, with mesoporous CoO being able to fully oxidize methane to CO and HO at 350 °C, while CoO@OMS exhibits a lower activity with 20 % conversion at 350 °C. CuO@OMS shows the lowest activity, with only ~13 % conversion at 500 °C. [ABSTRACT FROM AUTHOR]

Porous silica particles are often used as catalyst carriers in chemical reactions. Here, spherical porous silica particles with controllable pore size were synthesized by spray drying of nanocolloidal SiO2, using polyvinylpyrrolidone (PVP) as pore template. After spray drying, the particles were collected on a filter and then calcinated in a muffle oven to remove the template. The pore size and porosity of the SiO2-agglomerate can be tailored by the amount of PVP and the primary particle size of SiO2. [ABSTRACT FROM AUTHOR]

Ordered mesoporous material SBA-15 was synthesized and used as a support for the preparation of molybdenum sulphide catalysts through precipitation from homogeneous solution (PFHS) technique with the Mo content varying from 2-12 wt%. The prepared catalysts were evaluated for thiophene hydrodesulphurization catalytic activities at 400°C. Catalysts prepared through PFHS method resulted in highly dispersed MoS catalysts, which were inferred from powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature oxygen chemisorptions (LTOC) and BET surface area analysis. The relationship between XPS intensity ratio, oxygen chemisorption and catalytic activities is discussed in terms of highly dispersed nano particles of MoS and its consequence in accommodating more promoted atoms at the edge sites. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highlights: [•] We synthesized a new enzyme-responsive mesoporous silica material. [•] The materials showed “zero release” in SGF, SIF or PBS. [•] Large amounts of entrapped drugs released in the presence of azo-reductase. [•] The material showed excellent behavior for colon specificity. [Copyright &y& Elsevier]

Abstract: Nitrogen-doped hollow mesoporous carbon spheres has been synthesized from mesoporous silica spheres using glycine as carbon and nitrogen precursor. The wall of the spheres is composed by broken graphene. The metal free nitrogen-doped hollow mesoporous carbon spheres are proven to be active electrocatalyst for the oxygen reduction reaction in alkaline solution. A unique advantage of the nitrogen-doped hollow mesoporous carbon sphere is its methanol-tolerant property because of the absence of active metal. The catalytic activity is ascribed to the pyridinic-nitrogen formed during pyrolysis and the graphene-like structure. To the best of our knowledge this is the first report on the nitrogen-doped hollow mesoporous carbon sphere as a metal-free electrocatalyst for the oxygen reduction reaction which is an important reaction in fuel cell. The prepared mesoporous carbon material can also be used as catalyst support and find application both in the anode and cathode of fuel cell. [Copyright &y& Elsevier]

Highlights: [•] Different fluorescent PPV@MSNs were synthesized by a facile strategy. [•] Novel core–shell structured fluorescent MSNs were successfully synthesized. [•] Different containing-PPV MSNs had excellent fluorescent properties and high PL QYs. [•] Novel fluorescent MSNs can be used in the controlled release and the cell imaging. [Copyright &y& Elsevier]

Highlights: [•] New experimental methodology is set for bonding tetrapyrroles to natural analogs. [•] Chlorophyll covalent bonding to SBA-15 or organo-modified silica is achieved. [•] Chlorophyll properties depend on the organic chain bonding it to a pore network. [•] Stable and fluorescent chlorophyll can be trapped within pore systems. [Copyright &y& Elsevier]

Abstract: Silica particles with uniform hexagonal mesopore architecture were synthesized by template directed sol–gel condensation of tetraethoxysilane or mixture of tetraethoxysilane and (3-chloropropyl)triethoxysilane in a water–ethanol–ammonia solution. Selective functionalization of exterior surface of parent materials was carried out by postsynthetic treatment of template-filled MCM-41 and Cl-MCM-41 with vapors of (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vacuum. The chemical composition of obtained mesoporous silicas was estimated by IR spectroscopy and chemical analysis of surface products of reactions. Characteristics of porous structure of resulting materials were determined from the data of X-ray, low-temperature nitrogen ad-desorption and transmission electron microscopy measurements. Obtained results confirm invariability of highly ordered mesoporous structure of MCM-41 and Cl-MCM-41 after their selective postsynthetic modification in vapor phase. It was proved that proposed method of vapor-phase functionalization of template-filled starting materials is not accompanied by dissolution of the template and chemical modification of pores surface. This provides preferential localization of grafted functional groups onto the exterior surface of mesoporous silicas. [Copyright &y& Elsevier]

Highlights: [•] Synthesis of sol–gel highly porous silica for adsorption of simazine from water. [•] Bringing agrochemical concentration below the law limit allowed in wastewaters. [•] Regenerating the adsorbent which can be used again in the iterative process. [Copyright &y& Elsevier]

Abstract: Three-dimensionally ordered macroporous silica microspheres were fabricated by colloidal crystal templating method. The colloidal crystals were assembled through the crystallization of monodisperse charged polystyrene (PS) particles during the evaporation of suspension droplets in the self-assembly process. Viscous silicone oil was used as dispersion medium to confine specific geometry. Followed by infusing silica precursor into colloidal crystals and a final calcination for PS removal, silica skeleton was formed in the interstices and macropores were left at PS′s sites. The macroporous silica made by this method was macroscopically spherical with a diameter of few tens of micrometers and the pores were close-packed and well-ordered in three-dimensions. This paper provides a facile technique to fabricate ordered colloidal crystal microballs and macroporous materials. [Copyright &y& Elsevier]

Abstract: In this work we report on the synthesis of porous amine functionalized organosilica materials prepared by co-condensation of tetraethyl orthosilicate (TEOS) and bis-[3-(trimethoxyosilyl)propyl] amine (BTPA). The gels were prepared through a one-step sol–gel process catalyzed by the NH groups of BTPA. A block copolymer poly(ethylene glycol)–block-poly(propylene glycol)–block-poly(ethylene glycol) (P123) was employed as a porogen using the surfactant template method. The resultant materials have been characterized by nitrogen gas sorption, powder X-ray diffraction, FT-IR, SEM, 29Si MAS NMR, 13C CP MAS NMR and TG/DTA analysis. In order to examine the potential of these materials as adsorbents for heavy metals, Hg(II) adsorption experiments were also performed. The hybrids showed mesoporous disordered structure as evidenced by N2 adsorption–desorption isotherms and XRD patterns. Adsorption of Hg(II) ions from aqueous solutions showed high capacities suggesting that these materials could be used as adsorbents for Hg(II) ions in acid solutions. [Copyright &y& Elsevier]

Highlights: [•] Highly ordered silica with small pores is synthesized and characterized. [•] Short-chain cationic–anionic mixed surfactant system was used as template. [•] Synthesis reported here should facilitate the large-scale applications of mesoporous silica with small pores. [ABSTRACT FROM AUTHOR]

Highlights: [•] Well-ordered porous cubic Ga-KIT-6 materials were synthesized by hydrothermal method. [•] Incorporation of gallium into KIT-6 material is suitable adsorbent for BTX removal. [•] Highly dispersed gallium precursor is the reason for high adsorption capacity. [•] The catalyst providing a higher adsorption capacity than SiO2 and activated carbon. [ABSTRACT FROM AUTHOR]

Mesoporous silica, due to its porosity and morphological features, have been considered a fascinating material for many technological applications. In this report, we describe the preparation of a structurally stable mesoporous silica material using octahydridooctasilsesquioxane (T). The structure and properties of final samples were determined by XRD, FT-IR, and TEM methods. Structural analysis has shown that the siliceous material is amorphous but mesoporous. BET surface area, pore volumes, and pore size distribution were measured using nitrogen sorption methods-data were collected from the adsorption branch using BJH method for mesopores and t-plot method for micropores. It was found that the cage-type structure of T molecules and the process conditions determine the specific morphology of the cross-linked products. Completely inorganic, mesoporous silica of a narrow pore distribution was obtained. It was found that the materials have large surface area and pores in the meso range (2-5 nm). The amount of mesopores and the characteristic surface area of the prepared samples strongly depended on the reaction conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fully capped mesoporous silica (FCMPS) with a core–shell structure was prepared. [•] SBA-15 is the core; linked polyhedral oligomeric silsesquioxanes is the shell. [•] FCMPS has higher porosity and bigger BET surface area than SBA-15. [•] FCMPS has significantly improved thermal and dielectric properties than SBA-15. [•] FCMPS/bismaleimide hybrids have stable and very low dielectric constant and loss. [Copyright &y& Elsevier]

Highlights: [•] Carboxyl-functionalized mesoporous silica-carbon composites have been synthesized. [•] The oxidized carbon layer coats uniformly the silica pores. [•] These materials retain the structural properties of the original mesoporous silica. [•] The carbon layer is highly functionalized with acid oxygen-containing groups. [•] These materials behave as excellent adsorbents towards basic dyes and heavy metals. [Copyright &y& Elsevier]

Highlights: [•] Hierarchically porous silica (HPS) was synthesized by a phase separation paralleling to the sol–gel transition. [•] The Fe2O3/HPS hybrids were prepared by the wetness impregnation method using HPS as a high performance carrier. [•] The Fe2O3/HPS hybrids showed high performance photocatalyst for Fenton reaction and exhibited an ideal stability. [Copyright &y& Elsevier]

Highlights: [•] Mesoporous silica nanospheres (MSNs) were functionalized by CaTiO3:Pr3+ by sol–gel method. [•] CaTiO3:Pr3+@MSNs nanospheres synthesized at 700°C possess both mesoporous and long-lasting phosphorescence properties. [•] CaTiO3:Pr3+@MSNs nanospheres can be observed in vivo. [•] CaTiO3:Pr3+@MSNs nanospheres can be used as sustained drug delivery system. [•] The drug release process can be monitored by detecting the phosphorescence intensity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis of uniform and thickness-controlled core–shell composites of mesosilica and USY zeolite. [•] The way ensures Y zeolite has least dealumination and keeps its original acidity after assembled. [•] The composites exhibit an excellent selectivity of middle distillates in hydrocracking of heavy oil. [•] Illustrating the self-assembly process of composites and the reason for high catalytic selectivity. [•] The way can be applied to assemble SBA-15 silica with some materials of nonresistant to acid. [Copyright &y& Elsevier]